franky
|
| posted on 5/7/11 at 09:16 PM |
|
|
High speed stability...
Woohoo my fist completed car post
Anyway, how do you improve high speed stability on a 7 type car? 130+mph?
I've raised the rear a little(15mm) as it was at the same height as the front(a oversight by me).
Running 6deg caster, 0.25deg toe out, 2 deg rear toe in, front 1.0 deg camber, rear 0.5 deg camber.
The car runs Ginetta G20 geometry but with wider track.
I guess raising the rear should have helped a lot.
I've not covered the whole underside of the car yet, engine bay is open underneath as is the very rear of the car.
I must say it was rock solid upto around that sort of speed, the steering just started to go light.
|
|
|
|
|
chrisxr2
|
| posted on 5/7/11 at 09:25 PM |
|
|
How fast??
To be honest i think the aerodynamics of the 7 type car are its worst enemy, and there is a limit to what you will achieve. I would be bloody
terrified to be doing 130 in my haynes roadster to be honest.
|
|
|
franky
|
| posted on 5/7/11 at 09:29 PM |
|
|
quote:
Originally posted by chrisxr2
To be honest i think the aerodynamics of the 7 type car are its worst enemy, and there is a limit to what you will achieve. I would be bloody
terrified to be doing 130 in my haynes roadster to be honest.
Its not about the top speed, just aiming to get the car set up as good as possible. I'm not sure what it will do flat out and not sure that
i'm brave enough to find out.
I'm guessing it will make it feel even more planted at 90+.
|
|
|
blakep82
|
| posted on 5/7/11 at 09:32 PM |
|
|
i thought 130 was usually about the top speed for 7s?
seems you need a little force on the front, what about those little 'canard' (?) things that go on the nose, just like small wings to push
the front down a little?
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
|
|
|
A1
|
| posted on 5/7/11 at 09:33 PM |
|
|
er...id lose the toe, but thats a personal thing, apart from that venting the front cycle wings, undertray/splitter is the best way to go, just try to
minimise lift. a diffuser would also help
|
|
|
franky
|
| posted on 5/7/11 at 09:40 PM |
|
|
quote:
Originally posted by blakep82
i thought 130 was usually about the top speed for 7s?
seems you need a little force on the front, what about those little 'canard' (?) things that go on the nose, just like small wings to push
the front down a little?
I've thought about those, not sure how much they actually do help though. Why 130? Don't the higher powered cars go quicker?
I did try it with zero toe but I prefer the way it feels with a tiny bit of toe out. I'll try it again at 0 to make sure.
Venting the front cycle wings isn't something I had thought about but makes perfect sense, cheers
[Edited on 5/7/11 by franky]
|
|
|
blakep82
|
| posted on 5/7/11 at 09:54 PM |
|
|
it around the 130-150 speed i think. to do with the aerodynamics, it takes a LOT more power to go much quicker.
but, flattening the bottom of the car, and a diffuser will help too
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
|
|
|
craig1410
|
| posted on 5/7/11 at 09:55 PM |
|
|
One of the best things you can do (I have read) is to modify the cycle wings to ensure that the airflow separates on the trailing edge otherwise it
develops lift.
Something like this: http://www.fluke-motorsport.co.uk/carbon-fibre-csr-style-cycle-wing-suitable-for-caterhams-westfields-etc-p-1034.html
Hope this helps,
Craig.
|
|
|
Chippy
|
| posted on 5/7/11 at 10:17 PM |
|
|
I had pretty much the same problem, and got over it this way, (see pic), and it worked a treat. HTH Ray
[img]
 
Near side view
[/img]
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
|
|
|
Guinness
|
| posted on 6/7/11 at 06:45 AM |
|
|
I fitted a diffuser to the rear, and it certainly made the back end feel more settled at high speeds.
However, it magnified the steering going light at 120+, so I think you'd have to do something at the front to balance it.
If I had more cash I would have looked at those carbon canards for the front nose cone plus some shaped cycle wings.
If you are putting a removable flat floor beneath the engine bay, you could extend it out at the front to form some sort of splitter / wing? Nothing
massive, just a couple of inches out from the bodyline / nose??
|
|
|
franky
|
| posted on 6/7/11 at 07:29 AM |
|
|
Cheers gents for all the suggestions/ideas. I know it'll never be rock solid at silly speeds. I just want it to feel good till the acceleration
dies off a little.
So far, Diffuser/undertray/vented wings all seem like bits that I can have a go at making myself.
With the stick on bits for the nose cone how much downforce can they give on a GRP nosecone that isn't rigid, I thought it might just flex?
|
|
|
britishtrident
|
| posted on 6/7/11 at 07:44 AM |
|
|
I would also get rid of the toe-out on the front.
|
|
|
ashg
|
| posted on 6/7/11 at 08:43 AM |
|
|
i have got 0.5 deg toe in on the roadster. it massively improved the high speed stability at the sacrifice of a little bit of turn in feel. mine will
do 150 in 5th at which point it hits the redline. im planning to fit different diff which should give me another 10mph then i can wang the boost right
up to give more torque to overcome the heavier gearing.
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
|
|
|
hughpinder
|
| posted on 6/7/11 at 09:09 AM |
|
|
I had some details of those 'csr' type front wings like the ones craig1140 links to. If I remember correctly caterham claim the lift from
the front wings was reduced by something like 40% at the top speed of the csr.
Regards
Hugh
|
|
|
steve m
|
| posted on 6/7/11 at 09:30 AM |
|
|
My stability has improved 99% by having zero toe in,
But the thought of doing 130 mph in my 7 is horrific,
100 is well fast enough with sitting 4" off the road
|
|
|
Irony
|
| posted on 6/7/11 at 09:40 AM |
|
|
I bet good money your lady hasn't seen this thread.
|
|
|
franky
|
| posted on 6/7/11 at 03:19 PM |
|
|
quote:
Originally posted by Irony
I bet good money your lady hasn't seen this thread.
Why would she be on LCB!>
Some good ideas gents for me to work at
|
|
|
scutter
|
| posted on 6/7/11 at 04:09 PM |
|
|
When I'm running on track , after fitting the rear tray I moved from small from number plate to standard size. It's mounted at an angle
under the nose, the change in size is noticeable above 100.
ATB Dan
The less I worked, the more i liked it.
|
|
|
franky
|
| posted on 6/7/11 at 05:14 PM |
|
|
Front numberplate angled back? I've not put a numberplate on the front yet as I've not decided where I want to place it, I guess this
may help.
|
|
|
scutter
|
| posted on 6/7/11 at 05:35 PM |
|
|
 
scoop
This is the small plate, it has a substantial mounting system.
Dan.
[Edited on 6/7/11 by scutter]
The less I worked, the more i liked it.
|
|
|
norfolkluego
|
| posted on 6/7/11 at 05:58 PM |
|
|
Surely a high top speed and a 7 are a bit incompatible. If you want that you'd be better off with a cheap 944 or 200SX.
Thing is who wants to go fast in a straight line anyway, that's easy, what you want sir is to go round corners very, very quickly, that's
where the fun is and at that a 7 is awesome.
|
|
|
David Jenkins
|
| posted on 6/7/11 at 06:09 PM |
|
|
quote:
Originally posted by norfolkluego
Thing is who wants to go fast in a straight line anyway, that's easy, what you want sir is to go round corners very, very quickly, that's
where the fun is and at that a 7 is awesome.
As proved on Sunday, coming back from the Suffolk BBQ - I was driving along an open country road, when a large Vauxhall came up behind me, positioning
himself quite aggressively - too close, too pushy. I ignored him for most of the time, except when I had a couple of sharp 90-degree corners to
negotiate... which I took at the max speed at which I was comfortable. After which the pillock behind was trailing a couple of hundred yards back...
Oh yes - as said above - and toe-out will not help with straight-line stability - in fact, it will make it quite twitchy. I found my car much more
civilised once I'd set it with a little bit of toe-in. You do lose a little bit of steering 'pointability' but the comfort factor
when cruising in a straight line is a bonus.
[Edited on 6/7/11 by David Jenkins]
|
|
|
A1
|
| posted on 6/7/11 at 07:22 PM |
|
|
If you have toe out on the front, youll get better turn in, but the downside is you lose straight line stability, Dont think i read the post properly
last night, but thatd make a big difference in itself.
|
|
|
franky
|
| posted on 6/7/11 at 08:14 PM |
|
|
quote:
Originally posted by norfolkluego
Surely a high top speed and a 7 are a bit incompatible. If you want that you'd be better off with a cheap 944 or 200SX.
Thing is who wants to go fast in a straight line anyway, that's easy, what you want sir is to go round corners very, very quickly, that's
where the fun is and at that a 7 is awesome.
I understand what your saying but it seems I can have both, thanks to mr GKD and mr BMW it's doing 35mpg too so its now green!
On the list;
1 the toe at the front to zero
2 fit a front number plate(should be at the top I guess officer)
3 fit an under tray to the front(once minor leaks are sorted)
4 Make a diffuser of some kind, I wouldn't want anything too in your face though, discreet would be nice
|
|
|
britishtrident
|
| posted on 6/7/11 at 08:24 PM |
|
|
Front toe should be set just on the toe-in side of parallel.
The other thing nobody has mention is bump steer ... but try toe-in first.
|
|
|
